Gas chromatography with a mass detector is the most widely quoted analysis in a contract laboratory's catalogue, and the number on the quotation is the smallest part of what it costs. The consumables are continuous, the method development is once but expensive, and the second-hand market is large enough that the buy-or-send-out decision is genuinely open. This page separates the price of an analysis from the price of the capability, and says what to check in each case.
GC MS vials, septa and the autosampler that punctures them
The sample container is the least glamorous and most reliable source of a bad result. Crimp caps seal better and screw caps are faster; both use a septum that cores after a number of punctures and drops fragments into the sample. Low-volume work needs an insert rather than a smaller vial, because the autosampler needle depth is fixed and a shallow pool is what an empty injection looks like. Buy one specification and stay on it: a change of vial supplier has ended more methods than a change of column.
What a gas chromatography mass spectrometry price includes, and what the gc ms price on a quotation leaves out
A per-sample figure normally covers the run, the data and a report against an established method. It does not usually cover method development for a matrix the laboratory has not seen, the reference standards your analyte needs, sample preparation beyond a stated simple case, or a rush. Ask which of those four apply before comparing two quotations, because the cheaper number is frequently the one that assumes an existing validated method and the dearer one is the number that includes building it.
A gc mass spectrometer price against used gcms stock
New instruments are quoted as a configuration rather than a product, and the detector, the autosampler, the software licence and the installation are separable line items. The used market is deep because laboratories replace on a service cycle rather than on failure, so a well-maintained instrument a few years old is genuinely serviceable. What decides the comparison is not the capital but the service contract: an instrument the manufacturer will no longer support is a consumable, however well it runs today.
When a GC-MS test and GC/MS testing mean different things
A single determination and a testing programme are priced and validated differently, and the words are used interchangeably in enquiries. A one-off screen answers whether something is present in this sample, against a method the laboratory already holds, and carries the uncertainty of that method. A programme means a method validated in your matrix, a control strategy, and a record that will stand up later. Say which you are buying, because a screen reported as a programme is the commonest reason a result cannot be used.
Used gc ms instruments, and what to check before buying
Ask for the service history and the last performance check rather than the running hours. Get the pump and source condition, whether the instrument has been vented and how often, what software version it runs and whether that version is still licensed and installable, and which consumables and spares are still made. Run a real sample before money changes hands if the seller will allow it. A cheap instrument that needs a source rebuild and an unobtainable board is not cheap.
Headspace GC MS, where the sample never reaches the column
For volatiles in a difficult matrix the sample is heated in a sealed vial and only the vapour above it is injected, which removes the sample preparation and most of the contamination at once. It also changes what is measurable: partition between the liquid and the headspace is temperature and matrix dependent, so quantification needs standards in a matching matrix rather than in solvent. It is the right technique for residual solvents and for anything where the matrix would destroy a column, and the wrong one for a semi-volatile.
Questions people ask about gc ms analysis
Why do two laboratories quote so differently for the same analysis?
Usually because one has an established validated method for your matrix and the other is pricing in the development. Ask each whether the quotation includes method development, reference standards and sample preparation, and the numbers normally converge.
Is buying cheaper than sending samples out?
It depends on throughput and on whether you have the method. The instrument is the smaller half: the analyst time, the standards, the consumables and the service contract are continuous, and a method you do not yet have is a project. Below a few hundred samples a year a contract laboratory is usually cheaper.
What is the first thing to check on a second-hand instrument?
Whether the software version it runs is still licensable and installable on a supported operating system. An unlicensable instrument cannot be used whatever its condition, and this is the failure people discover after delivery.